This study aims to clarify the effect of mortar intrinsic properties (porosity, roughness and carbonation level) on its ability to biofouling. Two scales experimental tests, an accelerated fouling in laboratory and a natural fouling in the real-world, were set-up. The first one was conducted in a closed device allowing a periodic sprinkling of an algal suspension on the samples surface. The outdoor test samples were exposed in a park at Grenoble (France). The colonization rate of the sample surface was evaluated by image analysis. The results show that the impact of each intrinsic parameter is quite different as function of the test. The porosity has no influence on the algal colonization of the samples exposed in indoor whereas a high porosity seems to increase slightly the bioreceptivity of ones exposed outdoor. The roughness, in both tests, promoted the microorganisms attachment and so their colonization. However, the discrimination of roughness grades is higher in the laboratory test than in the in-situ one. The surface pH significantly influences on the accelerated biofouling but not on the in-situ one. These dissimilarities result from the difference in experimental configurations of the two tests. Thus the laboratory test should be adjusted to be more suitable and to allow an extrapolation of results.